
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>输入两个数字，比较大小</title>
<style>
body{font:12px/1.5 arial;text-align:center;}
.f-text{width:50px;border:1px solid #ccc;background:#f0f0f0;font-family:inherit;padding:3px;}
.f-btn{margin:0 10px;}
strong{padding:0 10px;}
span{font-weight:700;color:red;}
</style>
<script type="text/javascript">
window.onload = function ()
{
	var aInput = document.getElementsByTagName("input");
	var aSpan = document.getElementsByTagName("span")[0];
	var i = 0;
	
	for (i = 0; i < aInput.length - 1; i++)
	{
		aInput[i].onkeyup = function ()
		{
			this.value = this.value.replace(/[^\d]/,"")
		}	
	}
	
	aInput[2].onclick = function ()
	{
		/*未输入数字时，按钮的提示*/
		(aInput[0].value == "" || aInput[1].value == "") ?
		alert("请输入数字！") :
		/*使用了math对象中max数据对比的方法*/
		(aSpan.innerHTML = Math.max(aInput[0].value, aInput[1].value)) ;
	}
};
</script>
</head>
<body>
<input type="text" class="f-text" /><strong>vs</strong><input type="text" class="f-text" /><input type="button" value="最大的数是 &raquo;" class="f-btn" /><span>？</span>
</body>
</html>
